Distance rate and multi-year claims

Hello,

We've noticed some odd behaviour when trying to process mileage Expense Reports over a year-end and where multiple distance rates are used.

Scenario 1: second tier rate for 2020 has not been entered yet.

This is our Mileage Distance Rate setup:

As you can see I've intentionally excluded the second tier rate in 2020. Prior to entering my final mileage claim for 2019, this is the status of the Transportaion Info:

I have 500 km's left at 0.58 for 2019 and I haven't used any of the 5,000 km at 0.59 for 2020. When I try to enter the claim for 1,000 km in 2019 and 4,001 in 2020, I get the following error: